). Using a size-resolved wet scavenging parametrisation, the amount of BC on snow due to wet scavenging is estimated as 29 mg kg (1 for an accumulated snow depth of 27 cm. For the range of 10Á200 mg kg(1 of BC in snow, the diurnally averaged forcing due to snow darkening has been found to vary from 0.87 to 10.2 W m (2 for fresh snow and from 2.6 to 28.1 W m (2 for the aged snow, which is significantly higher than the DRF. The direct and surface albedo radiative forcing could lead to significant warming over the Himalayas during pre-monsoon.

The eustatic sea-level rise due to global warming is predicted to be about 18 to 59 cm by the 2100 (IPCC 2007), which necessitates identification and protection of vulnerable sections of coasts. Assessment of vulnerability level of Andhra Pradesh (AP) coast as an example is demonstrated in this study using five physical variables, namely coastal geomorphology, coastal slope, shoreline change, mean spring tide range, and significant wave height. A coastal vulnerability index was prepared by integrating the differentially weighted rank values of the five variables, based on which the coastline is segmented into low-, moderate-, high-, and very high risk categories. About 43% of the 1,030-km-long AP coast is under very high-risk, followed by another 35% under high-risk if the sea level rises by~0.6 m displacing more than 1.29 million people living within 2.0 m elevation in 282 villages in the region.

Snow cover in the Himalayan-Tibetan region is highly variable in space and time, and influences the hydrology and climate at regional and global scales. Monthly MODIS snow cover and land surface temperature (LST) data have been analysed for the period 2000-2011. The details of the snow cover pattern during accumulation and ablation has been studied for the Indus, Ganga and Brahmaputra river basins. These river basins have shown a unique pattern of snow accumulation and ablation. The Indus and Ganga Basins have shown high snow cover percentage than the Brahmaputra during ablation period. The maximum snow cover for the three basins altogether is approximately 85% of the total geographic area which reduces to approximately 10% during ablation. Accumulation and ablation variations are clearly depicted by the LST variations of the respective basins. However, the Indus Basin has shown a unique increasing trend in snow cover, whereas the Ganga and Brahmaputra Basins have shown no significant trend in this decade. Snow cover for Tibetan region during March (accumulation) and September (ablation) months have not shown either increasing or decreasing trend from 2000 to 2011. Analysis of monthly average basin LST data has shown that Indus Basin experiences subfreezing conditions and delay in rise of peaks in comparison to Ganga and Brahmaputra which shows high LST during accumulation. This study shows that the Indus, Ganga and Brahmaputra Basins have shown different patterns in the snow cover variations during the last 12 years.

ABSTRACT. Indian rivers originating in the Himalaya depend on seasonal snow-cover melt during crucial summer months. The seasonal snow cover was monitored using Advanced Wide Field Sensor (AWiFS) data of the Indian Remote Sensing Satellite (IRS) and using the Normalized Difference Snow Index (NDSI) algorithm.

River deltas are the major repositories of terrestrial sediment fl ux into the world's oceans. Reduction in riverine inputs into the deltas due to upstream damming might lead to a relative dominance of waves, tides and currents that are especially exacerbated by coastal subsidence and sea-level rise ultimately affecting the delta environment. Analysis of multi-date satellite imagery and maps covering the Krishna and Godavari deltas along the east coast of India revealed a net erosion of 76 km 2 area along the entire 336-km-long twin delta coast during the past 43 years 2000-2005. In the case of the Godavari delta, although the water discharge data do not show any major change, there was almost a three-fold reduction in its suspended sediment loads from 150·2 million tons during 1970-1979 to 57·2 million tons by [2000][2001][2002][2003][2004][2005][2006]. A comparison of data on annual sediment loads recorded along the Krishna and Godavari Rivers showed consistently lower sediment quantities at the locations downstream of dams than at their upstream counterparts. Reports based on bathymetric surveys revealed considerable reduction in the storage capacities of reservoirs behind such dams. Apparently sediment retention at the dams is the main reason for the pronounced coastal erosion along the Krishna and Godavari deltas during the past four decades, which is coeval to the hectic dam construction activity in these river basins.